Sheave suspension fixture for extension ladders



United States Patent [56] References Cited .UNITED STATES PATENTS [72] Inventor Hyman Kramer "a m u .ms R0 03 66 99 11 l/ 2 1| 9 005 51 91 23 [22] Filed June 10, 1969 Primary Examiner-Reinaldo P. Machado Attorney-J. Harold Kilcoyne A continuation-in-part of Ser. No. 723,418, Apr. 23, 1968, abandoned.

[45] Patented Oct. 27, 1 970 [54] SI-IEAVE SUSPENSION FIXTURE FOR EXTENSION LADDERS 4 Claims 6 Drawing Figs ABSTRACT: A fixture for suspending the sheave over which the rope employed to raise and lower the fly section of an extension ladder with respect to its ground section is trained,

Int. E06c 7/12 said fixture being of the non-swiveling type which is nonethe- [50] Field l82/207, less effective to dispose the turning axis of the sheave in the 208; 248/340 plane of said ground section.

Tlilllllll SHEAVE SUSPENSION FIXTURE FOR EXTENSION LADDERS This invention relates to improvements in extension ladder hardware, and more particularly hardware in the nature of a fixture for suspending the sheave or pulley over which the rope employed to hoist and lower the fly or upper section of an extension ladder with respect to its base section is trained, the present application for letters patent thereon being a continuation-in-part of my U.S. Pat. application Ser. No. 723,418, filed Apr. 23, .1968 and now abandoned.

As is well known. the fly, i.e. upper, section of an extension ladder is hoisted relative to its base or ground section by pull applied to the free end of a rope affixed atits other end to a lower rung of said fly section and which is trained over a sheavesuspended from an upper (usually the uppermost) rung of said ground section, with lowering of said fly section being effected, foll'owing unlocking of the ladder sections, by a controlled paying out of said rope. Because the reaches of the rope which extend between its fixed end and the sheave and thence between said sheave and its free end normally assume a rearwardforward relationship, Le. being disposed in a more or less common vertical plane which is at a substantial right angle to the planes of the sections, it is highly desirable, in the interest of freedom of action and prevention of chafing of the rope, that the sheave turn on a transverse axis which is contained generally in the plane of the ladder section mounting same, i.e. the ground section. Such favorable disposition of sheave axis is achieved in the more costly makes of extension ladders by suspending the sheave via a swivel-type suspension means which enables said sheave to bodily orient itself to a position in which its turning axis lies in the general plane of the ground section of the ladder, when any appreciable pull is applied to the rope.

However, the economics involved in the manufacture of the lower-priced extension ladders do not ordinarily permit use of .the aforesaid swivel-type suspension means, because of its relatively high cost. Instead, such ladders employ a simple sheave hang-bracket which fixedly disposes the turning axis of the rope sheave at a right angle to the plane of the section mounting same, as results in the reaches of the rope being turned generally to side-by-side relation, rather than in the more favorable rearward-forward relation, and such can result in the rope being short-lived due to chafing, rubbing, etc.

With the above in mind, a primary object of the invention is the provision of improved hardware for extension ladders in the form of a fixture for suspending the sheave over which the rope employed to hoist and lower the fly section of the ladder with respect to the base section is trained, and which is so constructed and arranged as to dispose the turning axis of the sheave generally in the plane of the base section of the ladder, and which is moreover so inexpensive in manufacture and simple to assemble that it may be incorporated into the lowerprice makes of extension ladders without any substantial increase in the cost thereof, and at the same time may, if desired, be usefully employed in the more expensive makes of extension ladders.

A more particular object of the invention is the provision of a suspension fixture for mounting the sheave of an extension ladder over which its fly section raising and lowering rope is trained,which is characterized by simple and durable yet inexpensive construction which is capable of being readily assembled to a rung of a ladder section as required and which, more importantly, disposes the turning axis of the sheave in a position favorable to the free running and hence reduction if not elimination of wear on the rope by which said fly section of said ladder is raised and lowered with respect to its ground section.

The above and other objects and features of advantage of a sheave suspension fixture for extension ladders according to the invention will be apparent from the following detailed description of two typical embodiments thereof selected for purpose of simple disclosure, taken with the accompanying illustrative drawings, wherein:

FIG. 1 is a broken-away elevation of a portion of an extension ladder employing a sheave suspension fixture according to the invention;

FIG. 2 is an enlarged fragmentary view showing the-rope sheave in side elevation and the fixture in end view, and also generally depicting the manner of assembling the fixture to the rung of a ladder;

FIG. 3 is a fragmentary view of the assembled sheave and fixture as seen from the front thereof;

FIGS. 4 and 5 are views corresponding to FIGS. 2 and 3 which show a somewhat modified construction of sheave suspension fixture as herein contemplated; and

FIG. 6 is a separated view of the parts making up the basic sheave suspension fixture according to the present invention.

Referring to the drawings in detail, a typical extension ladder for which an improved sheave suspension fixture as herein contemplated was devised comprises a ground section generally designated 10 provided by spaced-apart side rails 12a, 12b'and cross rungs I4, and an upper or fly section generally designated 16 provided by similar side rails 18a, 18b

and cross rungs 20, said sections being maintained in extensible and retractible relation, by means not shown. As is conventional, the fly section 18 is hoisted or extended .with respect to the ground section 10 so as to increase the length of the ladder by pull applied to the free end 22a of a rope 22 having its other end affixed as at 22b to a lower cross rung 20 of the upper section 16 and which is trained over a sheave or pulley 24 suspended from an upper (usually the topmost) rung of the ground section 10, the rope thence extending downwardly-forwardly from the sheave. By such an arrangement of ladder sections and rope, the fly section 16 may be hoisted with respect to the ground section 10 to increase the overall length'of the ladder by pull applied to said free end .of the rope, and thereafter said fly section may be lowered to effect shortening of the ladder by controlled paying-out of said rope from its free end.

From the above and a consideration of FIG. I, it will be appreciated that the reach of the rope extending upwardly from its fixed end 22!) to the sheave and the reach of the rope extending downwardly from said sheave to its free end 220 bear a distinct rearward-forward relationship, which makes it desirable that the sheave 24 turn on a transverse axis which is disposed generally in the plane of the ladder section mounting same, and more particularly in the plane of the base section 10 of said ladder.

To achieve said disposition of the sheave axis in simple and economical manner, the invention provides a sheave suspension fixture whose detailed construction is best shown in FIG.

6 and which is capable of being assembled to a ladder rung in.

the manner-shown in the remaining views. More particularly, a sheave suspension fixture as herein proposed comprises a fixture body generally designated 30 consisting of a length of relatively thin-gauge metal. strap having uniform width throughout its length which is bent to the form of an inverted U, thus to have a bight or connecting portion 32 and depen-- dent, generally parallelly disposed and initially spaced-apart planar side legs 34a, 34b, and an axle pin 50 cooperatively related thereto in manner such that it not only provides the turn ing axis for the sheave 24 but also secures said side legs 34a, 34b together; at least adjacent their free lower end portions. As best seen in FIG. 2, the aforesaid bight portion of the fixture body extends along a radius of curvature corresponding substantially to that of the particular ladder rung (14, FIG. 2) on which the fixture will be hung and thus, when placed in straddling relation on said rung, the fixture is more or less snugly fitted to same.

For the reception of the sheave 24 which the aforesaid fixs ture body is to mount, the dependent, parallelly disposed side legs 34a, 34b thereof are provided with vertically elongated, preferably rectangular openings or windows 36a, 36b whose height (vertical dimension) and width are somewhatgreater than the diameter and axial width, respectively, of said sheave. Moreover, the placement of said openings along the length and width of the fixture bodylegs in which they are provided is such that the openings register when the legs are brought togetherto their final positions shownin FIGS. 2 and 4. a

, With the aforesaid sheave-receiving openings 36a, 36b of the provision of said openings, in the fixture body legs as aforesaid in turn provides each leg with the pair of transversely spaced, vertically extending wbandlike: formations (hereinafter termed bands) which extend vertically along the opening sides. Thus. as seen in N66, the fixture-body leg 34a is provided with ,a pair of bandsdesignated38a; 40a which are disposed to the-opposite sides of its opening 360, and the fixture-body leg 34b is provided with a similar pair of transversely spaced bands designated 38b, 40b which extend along the sides of the opening 36b.

To effect mounting of the axle pin 50, the aforesaid bands are each provided in their middle portions with central, vertically disposed slits or cuts and thereupon the material of said bands disposed immediately to the sides of said cuts is worked to provide laterally offset, illustratively semicylindrical formations of opposite curvature, of which the formations of the band 38a are designated 42a, 42b; the formations of band 400 are designated. 44a, 44b; the formations of band 38b.are

designated 46a, 46b; and the'formations of band 40b are corresponding formations will nest with one another. that is to say, formation 42awill nest in formation 46a, formation 46b will nestin formation 42b, and so on. Such of course requires thatthe inner ones of the nested formation pairs will provide the bore opening for the axle pin,,while the outer ones must have somewhat enlarged diameter so .as 'to be. capable of receiving said inner ones, all as necessary for the nesting relationship.

From the above, it will be appreciated that to assemblea sheave suspension fixture according to the present invention fixture legs 34a,;34b together, thereupon position the sheave 24 in the openings 36a, 36b of said fixture-body legs with its axle-receiving bore generally aligned with the bore portions provided by the aforesaid bore formations 42a,-46b, etc., and

finally thread said axle pin 50 through the said bore portions and through the sheave bore. Whenthe parts are so assembled, the axle pin 50 functions not onlyfto providethe turning axis for the sheave 241but also additionally functions to maintain said initially spaced-apart lower ends of the side arms 34a, 34b of the fixture body 30 in close adjacency.

By closely fittingithe axle pin 50 to the inner ones of said nested formations 42a, 46b, etc., preferably by fitting said formations to said pin. the latter will be held in place by friction. Alternatively,.the ends of the axle pin may be peeried'over after the assembly of pin, sheave and fixture body 30 has been effected as aforesaid, thus insuring against the pin moving axially from the fixture body.

FIGS. 4 and 5 illustrate that, if desiredor considered advisable, the initially spaced-apart lower-end portions of the fixture body legs 34a, 34b may be held in their fully assembled position of close adjacency by means supplemental to the axle pin 50. More particularly. said legs may be secured one to the in FIGS. 2, 4 and 6.the corresponding formationsof theoppositely related bands 38a, 38b and 40a. 40b of the pairs thereof are so disposed that when said bands are brought into closeadjacency as they are shown to be in FIGS. 2 and 4, said means such as a rivet 52 passed throughsaid legs. To accom-. modate the latter, said legs will ordinarily be provided with rivet-receiving holes in the fabrication of the fixture body 30. 5 By reference toFlGS. ,l, 3 and 5 in particular, it'will be seen that a sheave suspension fixture as described disposes the sheave-mounting and turning axis, i.e. that of the axle pin 50, to extend transversely and in the vertical plane of the ground section of the ladder, and thus is fully effective to provide the rope which effects raising and lowering of the fly section 16 of the extension ladder shown with respect to its ground section. it will be appreciated also that a sheave suspension fixture according to the invention may befabricated ata fraction of the cost of the swivel-type sheave suspension fixture conventionally employed in extension ladders of the more expensive makes, but that despite its low cost, it provides the main advantages of the known swivel-type suspension fixtures, 20; Le. that of insuring free running of the rope and reduction in chafing and wear thereon.

As many changes could be made in carrying out the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

lclaim:

1. In an extension ladder comprising a ground section and a cross rung of the fly sectionand extending upwardly' therefrom and being trained over a sheave suspended from an upper rung of the ground section and thence extending forwardly-downwardly from said sheave, the improvement comprising a fixture for suspending said sheave from said upper rung in position such that its turning axis extends transversely across and in the plane of said groundsection, said fixture including an elongate strap member of uniform width throughout its length and being benton itself to inverted U- shape and thus having a bight portion and dependent, norupper rung and said dependent side legs are provided with re- .gistering openings having length and width slightly greater than the diameter and axial dimension, respectively, of said defining pairsof vertically disposed,.laterally spaced bands, and said bands of the pairs thereof being provided with transversely aligned formations defining laterally spaced, shortlength bore openings for an axle pin providing the turning axis for said sheave, an axle pin threaded through said transversely aligned bore-defining formations, said sheave being accom- .modated in the registering openings of the side legs and saidaxle pin providing the turning axis therefor.

2. A sheave suspension fixture for an extension ladder according to claim I, wherein said boredefining formations of the pairs thereof are so shaped that the formations of one pair thereof both nest with and complementthe formations of the other pair thereof when the lower ends of said side legs are brought together, andwherein the construction and arrangement of parts is further such that said axle pin, when threaded through the transversely aligned bore-defining formations as.

aforesaid, operates to bring together ,and maintain the lower ends of said legs in substantial face-,to-face engagement.

, 3. A sheave suspension fixture for an extension ladder according to claim 2, wherein the bore-defining formations of ;the pairs thereof each comprises partial bore-defining formaone another in providing a full bore opening.

4. Ajsheave suspension fixture for an extension ladder according'to claim 3, wherein said partial bore-defining formations in side-by-side relation as aforesaid have opposite generally semicircular curvature.

the favorable rearward-forward relationship of the reaches of mallyspaced-apart planar side legs. of which said bight portion has curvature corresponding generally to that of said sheave, the side leg portions to the sides of said openings tions disposed in side-by-side. relationand which complement other at points thereon intermediate the r'tmgiin'daxie pin by: 

